target/linux/generic/pending-4.9/890-uart_optional_sysrq.patch

   1 From: John Crispin <john@phrozen.org>
   2 Subject: serial: do not accept sysrq characters via serial port
   3
   4 many embedded boards have a disconnected TTL level serial which can
   5 generate some garbage that can lead to spurious false sysrq detects.
   6
   7 [john@phrozen.org: sent upstream 22.12.2016]
   8
   9 Signed-off-by: John Crispin <john@phrozen.org>
  10 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  11 ---
  12  include/linux/serial_core.h | 2 +-
  13  lib/Kconfig.debug           | 5 +++++
  14  2 files changed, 6 insertions(+), 1 deletion(-)
  15
  16 --- a/include/linux/serial_core.h
  17 +++ b/include/linux/serial_core.h
  18 @@ -448,7 +448,7 @@ extern void uart_handle_cts_change(struc
  19  extern void uart_insert_char(struct uart_port *port, unsigned int status,
  20                  unsigned int overrun, unsigned int ch, unsigned int flag);
  21
  22 -#ifdef SUPPORT_SYSRQ
  23 +#if defined(SUPPORT_SYSRQ) && defined(CONFIG_MAGIC_SYSRQ_SERIAL)
  24  static inline int
  25  uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
  26  {
  27 --- a/lib/Kconfig.debug
  28 +++ b/lib/Kconfig.debug
  29 @@ -410,6 +410,11 @@ config MAGIC_SYSRQ_DEFAULT_ENABLE
  30           This may be set to 1 or 0 to enable or disable them all, or
  31           to a bitmask as described in Documentation/sysrq.txt.
  32
  33 +config MAGIC_SYSRQ_SERIAL
  34 +       bool "Enable magic SysRq key over serial"
  35 +       depends on MAGIC_SYSRQ
  36 +       default y
  37 +
  38  config DEBUG_KERNEL
  39         bool "Kernel debugging"
  40         help